Chain Drives Selection - Procedure

Chain drive Selection -
Using PSG Design Data Book

Type of Chain
13-10-2021 Chain Drives 2
Roller Chain is selected for the application

Determination of Transmission Ratio
Calculate transmission ratio (i) from
PSG Design Data Book P. No: 7.74
Select the Preferred transmission ratio from
PSG Design Data Book P. No: 7.74 based on the
calculated (i) value
Pinion : Small sprocket
Wheel : Large sprocket

Standard Number of Teeth on Pinion Sprocket (Z1)
For the preferred transmission ratio (i) from
select recommend number of teeth on sprocket (Z1)
Choose odd number of teeth

Standard Number of Teeth on Wheel Sprocket (Z2)
From the preferred transmission ratio (i) and recommend number
of teeth on sprocket (Z1) calculate number of teeth on wheel (Z2)
using the formula in
PSG. Design Data Book P. No. 7.74
Choose even number of teeth

Selection of standard pitch (p)
Using the formula of optimum centre distance in
PSG. Design Data Book P. No. 7.74
and calculate pitch value (p)
After calculating pitch value, from
select standard pitch value
Select a random value between 30 to 50 or take average value for calculating "p"
if "a" value is not given assume a value(say 500 mm or 1000 mm)

Calculation of Breaking Load (Q)
Rearrange the formula for Power Transmitted in PSG Design Data
Book P. No: 7.77 and calculate breaking load in kgf
For calculating ks - use formula in page no. 7.76 & 7.77
Calculate speed "v" using formula
𝒗 =
𝒁𝟏𝒏𝟏𝑷
𝟔𝟎∗𝟏𝟎𝟎𝟎
Select minimum factor of safety "n" based on the values of pitch and
speed of small sprocket in PSG Design Data Book P. No: 7.77

Selection of Chain
Based on the calculated breaking load and pitch value
select the Roller chain from
PSG Design Data Book P. No: 7.71 to 7.73

Check for factor of safety
Using the formula in PSG Design Data Book P. No: 7.78 actual factor of safety
If the calculated actual factor of safety is greater than minimum factor of safety,
then the design is safe
w - select it based on the chain selected from PSG Design Data Book P. No: 7.71 to 7.73
k (coefficient of sag) - select it from PSG Design Data Book P. No: 7.78

Check for bearing stress
Using the formula of power transmitted in PSG Design Data Book P. No: 7.77
calculate bearing stress
Select the allowable bearing stress from PSG Design Data Book P. No: 7.77 based on
speed of small sprocket and pitch value
If the calculated bearing stress is less than allowable bearing stress, then the design is
safe
A - select it based on the chain selected from PSG Design Data Book P. No:
7.71 to 7.73

Calculation of actual length of chain
Using the formula in PSG Design Data Book P. No: 7.75 calculate actual length
of chain
lp - calculate it using the formula in PSG Design Data Book P. No: 7.75
ap - calculate it using the formula in PSG Design Data Book P. No: 7.75

Calculation of exact centre distance
Using the formula in PSG Design Data Book P. No: 7.75 calculate
exact center distance
e - calculate it using the formula in PSG Design Data Book P. No:
7.75
m- calculate it using the formula in PSG Design Data Book P. No:
7.75

Calculation of pitch diameter of sprockets
Using the formula in PSG Design Data Book P. No: 7.78 calculate
pitch diameter of sprockets

Problems for Practice
1. Design a chain drive to actuate a compressor from 15 kW electric motor running at 1000
r.p.m., the compressor speed being 350 r.p.m. The minimum centre distance is 500 mm.
The compressor operates 16 hours per day. The chain tension may be adjusted by shifting
the motor on slides.
2. Design a roller chain to transmit power from a 20 kW motor to a reciprocating pump. The
pump is to operate continuously 24 hours per day. The speed of the motor is 600 r.p.m.
and that of the pump is 200 r.p.m. Find: 1. number of teeth on each sprocket; 2. pitch and
width of the chain.
3. Design a chain drive to run a blower at 600 r.p.m. The power to the blower is available
from a 8 kW motor at 1500 r.p.m. The centre distance is to be kept at 800 mm.

Reference
• Machine Design by RS Khurmi and GK Gupta
13-10-2021 15

B.Varun
9787608011
bvarun.me@gmail.com
varun.me@srit.org
varunnelson bvarun.me
varunme bvarunme

Chain Drives Selection - Procedure

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